The purpose of this study is to determine whether individuals exposed to ethylene dichloride in the work place metabolize ethylene dichloride in a manner similar to either chlorzoxazone or dextromethorphan. Dextromethorphan has been used in vivo to demonstrate the presence of rapid and slow metabolizers in the population. It is hoped that this study will demonstrate metabolic patterns for the drugs and ethylene dichloride, such that workers exposed to ethylene dichloride can be predicted in advance of exposure.